Pushbutton interlocks



,1966 c. c. DAVIS PUSHBUTTON INTERLOCKS 2 Sheets-Sheet 1 Filed Aug. 4, 1964 v {WNW M U E 5.

Aug. 30, 1966 c. c. DAVIS 3,269,209

PUSHBUTTON INTERLOCKS Filed Aug. 4, 1964 2 Sheets-Sheet 2 United States Patent M 3,269,209 PUSHBUTTON INTERLOCKS Charles C. Davis, Brookfield, Wis., assignor to Cutler, Hammer, Inc., Milwaukee, Wis., a corporation of Delaware Filed Aug. 4, 1964, Ser. No. 387,434 3 Claims. (Cl. 74483) This invention relates to pushbutton interlocks.

Electrical pushbutton stations are often provided with two or more pushbuttons for operating mechanially independent switohes. If the switches control diverse modes of operation of the same control system then mechanical interlocking of the switches, or their pushbutton operators is usually provided to insure against concurrent conflicting operation of both switches. Mechanical interlocking of the pushbuttons so that one can not be depressed while another is in depressed position is the more usual arrangement and have taken various forms. In many cases use of interlocking requires building of special models for interlocking and non-interlocking service.

It is a primary object of the present invention to provide multiple pushbutton devices to which mechanical interlocking can be optionally added between any two adjacent pushbuttons by addition of but a single part.

Another object is to provide a novel and simple mechanical interlock for use between adjacent pushbuttons.

Other objects and advantages of the invention will hereinafter appear.

The accompanying drawings illustrate a preferred embodiment which will now be described in detail it being understood that the embodiment illustrated is susceptible of various modifications without departing from the scope of the appended claims.

In the drawings:

FIGURE 1 is a front view of a pushbutton device incorporating the invention;

FIG. 2 is a rear view of the inside of the enclosing cover for the pushbutton device;

FIG. 3 is a sectional view taken along the line 3-3 of FIG. 1;

FIG. 4 is a fragmentary View similar to FIG. 3, but

showing the device in a different operating condition;

FIG. 5 is an isometric view with one side of the enclosing cover broken away and certain parts shown in disassembled relation; and

FIG. 6 is a view like FIG. 4 showing the invention as applied to a three pushbutton device.

The drawings show a pushbutton device comprising a metal base or frame 10 and a U-shaped, wrap-around cover 12 formed of a molded insulating material. A dual momentary type of electric switch unit 14 having individual switch actuators 14a and 14b is mounted on the base 10 within the confines of cover 12. Pushbuttons 16 and 18 are mounted in cover 12, in a manner that will hereinafter be described in detail, and have inwardly projecting actuator portions 16a and 18a, respectively. Portions 16a and 18a. are alined with switch actuators 14a and 14b, respectively, and are adapted to depress the latter for switch actuation when buttons 16 and 18 are depressed inwardly of cover 12. Cover 12 is secured to base 10 by screws 20 which penetrate openings in the Patented August :30, 1966 Interlock discs 28 preferably formed of nylon are adapted to roll in such slots as will hereinafter be explained.

Buttons 16 and 18 on their insides are of the form best shown in FIG. 5. At opposite sides are inwardly extending skirt portions 161) and 18b. Integral projections 16c and which extend outwardly from the innermost ends of such skirts are adapted to engage within the recesses 38 formed between portion 28 and the parallel transverse portions 32 and 34 to limit the outward movement of the buttons in cover 12.

Springs 36 seat at corresponding ends in annular recesses 16d and 18d in buttons 16 and 18 and at their opposite ends bear against a retaining plate 38 which is secured to portion 26 by a screw 40. .Plate 38 has the pairs of down-turned ears 38a which center and restrain the springs 36 against lateral displacement on the plate. The extensions 3% overlie and close the outer sides of the slots 26a and 26b. Notches 38c on the opposite ends of plate accommodate the projections 32a and 34a of portions 32 and 34 which restrain the plate against rotational movement in cover 12. Rectangular openings 38d provide clearance for actuating portions 16a and 18a of buttons 16 and 18.

In assembling the device pushbuttons 16 and 18 are first inserted into openings 22 and 24 from the rear side of the cover. Next the springs 36 are seated in the recesses 16d and 18d, then interlock discs 28 are placed in slots 26a and 26b, and finally plate 38 is seated in place and screw 40 taken down into the portion 2-6 to secure the assembly together.

FIG. 3 shows both of the buttons 16 and 18 in extended position. With the device mounted on a vertical panel interlock discs 28 move under gravity bias into an inter ferring relation with button 18. However, when button 18 is depressed the discs 28 roll or slide in the slots 26a and 26b into an interferring relation with button 16 as shown in FIG. 4. So long as button 18 is maintained in depressed position inward depression of button 16 will be prevented by the discs 28. It will be apparent that discs 28 will provide the same blocking action on button 18 if button 16 is first depressed and held depressed.

While in the preferred form disclosed, two discs 28 have been used, this is not necessary and one disc 28 between adjacent pushbuttons will normally suflice, when the buttons are of a round or square outer configuration. It will be observed that if interlocking action between buttons 16 and 18 is not needed for a particular application the discs 28 can be omitted from the assembly. On the other hand, if subsequent field change in control circuitry should make interlocking action necessary or desirable, it can be readily obtained by merely removing cover 12, removing plate 38, inserting discs 28 and then reassembling the plate 38 and cover 12 in'reverse order.

FIG. 6 shows the use of the invention in conjunction with a three pushbutton switch device. More particularly, the device has three pushbuttons 50, 52 and 54 mounted in a cover 56. Springs 58 biases the buttons to outwardly extended positions in the cover. The buttons 50, 52 and 54 have actuating portions 58a, 52a and 54a which are engageable with the actuators 60a, 60b and 60c of mounting type switches mounted in the triple momentary switch 60. A spring retainer plate 62 secures the buttons in place in the cover. Pairs of slots 64, like slot 26a, extend between the recess in which button 52 moves and each of the recesses in which buttons 50 and 54 move. Discs 66, like discs 28, are mounted in each of the slots.

It will be apparent that with this arrangement prior depression of center pushbutton 52 will prevent inward depression of the other two, i.e., 50 and 54. Similarly, prior depression of either of the pushbuttons 50 or 54 will prevent depression of button 52 but not the other of the top or bottom-most pushbuttons.

I claim:

1. In a pushbutton device, a support having at least two openings extending theret-hrough, pushbutton operators mounted in each of said openings, a slot extending transversely between said openings, a disc having a diameter greater than the length of said slot between said openings disposed in said slot, springs bearing at corresponding ends against each of said pushbuttons, and a plate secured to said support which closes the open side of said slot and which bears against the other ends [of said springs to cause the latter to bias said pushbuttons outwardly of said support, said disc when either of said operators is depressed inwardly of said support being moved into an interferring relation with the other operator to block depression of the latter while the former is maintained in depressed position.

References Cited by the Examiner UNITED STATES PATENTS 1,040,705 10/1912 Leppert 74-483 X MILTON KAUFMAN, Primary Examiner. 

1. IN A PUSHBUTTON DEVICE, A SUPPORT HAVING AT LEAST TWO OPENINGS EXTENDING THERETHROUGH, PUSHBUTTON OPERATORS MOUNTED IN EACH OF SAID OPENINGS, A SLOT EXTENDING TRANSVERSELY BETWEEN SAID OPENINGS, A DISC HAVING A DIAMETER GREATER THAN THE LENGTH OF SAID SLOT BETWEEN SAID OPENINGS DISPOSED IN SAID SLOT, SPRINGS BEARING AT CORRESPONDING ENDS AGAINST EACH OF SAID PUSHBUTTONS, AND A PLATE SECURED TO SAID SUPPORT WHICH CLOSES THE OPENING SIDE OF SAID SLOT AND WHICH BEARS AGAINST THE OTHER ENDS OF SAID SPRINGS TO CAUSE 